The use of fans to move air through heat exchanges is well known, especially in the fields of air conditioning and motor vehicle cooling. In motor vehicles, the fans are typically used adjacent radiators in order to either push air or pull air through the radiator in order to cool liquids which are circulating through the engine and/or other accessories. The fans are typically driven by an electric motor or via a transmission from an associated engine in motor vehicles. The fans are usually disposed so that the radial plane of the fan extends parallel to a face portion or surface of the associated heat exchanger, such as a radiator. Fans of this type are commonly referred to as “axial flow fans”.
When the systems or vehicles are sold in substantial quantities, cooling fans made with plastic components or made entirely of plastic materials are designed and manufactured for each of the systems or vehicles—and are designed specifically for the particular air flow or that particular system or vehicle. The fans are provided of particular size and shape in order to optimize the air flow through the particular system or vehicle. Due to the large quantities in which the fans are provided, the cost of molds for even large fans are easily absorbed or amortized over the life of the vehicles and fan products. It is uneconomical, however, to provide large fans with molded plastic components for a particular system or vehicle (such as large trucks) which are not made or sold in substantial quantities.
Thus, it is an object of the present invention to provide an improved fan with molded plastic components which is less expensive to make and provide for systems and vehicles which are typically not sold in substantial quantities. It is another object of the present invention to provide a fan with a metal hub member and polymer fan blades which can be manufactured more easily and less expensively.